I think the most sensible answer is, having created the currency, and presumably, having watched its actions over the years, he'd probably be smart enough not to attempt to dump/swap/exchange all of his coins at once. If the goal was to have a billion dollars, then selling a million coins at market price at the same time would be the surest way NOT to reach that goal.
I assume s/he's still among us, and has plenty more coins aside from the fabled "satoshi" coins to do whatever they want with. But if those original coins did move, I don't get why there would be a freak out. Everyone came into the system knowing, or has since learned, that the mythological satoshi owns what he owns. If the day comes that they want to see some of the fruits of their labor, and that involves moving coins from the earlier blocks, why freak out any more than if they moved coins from later blocks?